Oh that's weird, for what platform are you trying to download it?
It may be the itch.io servers that weren't working properly and that would explain why the download failed. I can't do nothing about that since that goes from itch.io part.
Could you try downloading it again from the beginning? Make sure you delete all previous data. Maybe it failed midway and got corrupted. I'm sorry for that, once again, it could have been a problem in itch.io servers or something. If the problem keeps going I'll try to upload a new version again just in case, although when I test them they seem to work just fine, but you never know.
Thank you for reporting this and sorry for the inconveniences.